Process for producing thin polymer film by pulsed laser evaporation

Claim 2

In a process for producing a thin film of an addition polymer on a substrate by bombarding a target polymer with radiation from a pulsed laser in a vacuum or gas atmosphere to form a plume of the components of the target polymer which undergo a repolymerization reaction and are deposited on the substrate as a film, wherein the improvement comprises modifying the molecular weight of the addition polymer of the deposited film by conducting the deposition in the presence of at least one additive comprising a chain transfer agent or polymer initiator.

Claim 3

The process of claim 1 wherein the additive is coated on the substrate prior to deposition.

Claim 4

The process of claim 1 wherein the additive is introduced as a gas into the atmosphere of the repolymerization.

Claim 5

The process of claim 1 wherein the chain transfer agent is a mercaptan.

Claim 6

The process of claim 4 wherein the chain transfer agent is 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, butyl mercaptan, bromotrichloromercaptan, chloroform, or cyclohexane.

Claim 7

The process of claim 1 wherein the initiator is a hexaarylbiimidazole.

Claim 8

The process of claim 1 wherein the initiator is 2,2',4,4'-tetrakis(o-chlorophenyl)-5,5'-bis(m,p-dimethoxyphenyl)biimidazole; 2,2'-bis(o-cholorphenyl)-4,4',5,5'-tetraphenylbiimidazole; 2,2'-bis(o-chlorophenyl)-4,4',5,5'-tetrakis(m-methoxyphenyl)biimidazole; perfluoropropyl peroxide; perfluorobutyl peroxide; hexafluoropropylene oxide oligomer peroxide; benzoic peroxide; or azo-bis-isobutrylnitride.

Claim 9

The process of claim 1 wherein the substrate is maintained at a temperature about 100° C. above the glass transition temperature of the target addition polymer.

Claim 10

The process of claim 1 wherein the substrate is maintained at a temperature about 75° C. below the crystalline melting temperature of the target addition polymer.

Claim 11

The process of claim 1 wherein the pressure is maintained below about 33.3 Pascals during the deposition.

Claim 12

The process of claim 1 wherein the target polymer comprises a fluoropolymer, alkylacrylic polymer, or polyethylene.

Claim 13

The process of claim 11 wherein the target polymer comprises polymethylmethacrylate; polyethylmethacrylate; polybutylmethacrylate; polytetrafluoroethylene; a compound of Formula I wherein R 1 , R 2 , or R 3 is perfluoromethyl; a compound of Formula I wherein R 1 , R 2 , or R 3 is perfluoropropylvinylether; a copolymer of polytetrafluoroethylene and perfluoro-2,2-dimethyl-1,3-dioxol; a copolymer of polytetrafluoroethylene and bis-2,2-trifluoromethyl-4,5-difluoro-1,3-dioxole; a copolymer of polytetrafluoroethylene and hexafluoropropylene; or a copolymer of tetrafluoroethylene and perfluoroalkoxy monomer.